Todd Bowles, from everything I've heard on him from friends in Dallas and Miami, is a very respected coach. Very intelligent and great with his players. His players always play hard for him and love the guy.
He's not a fiery, rah-rah type of guy, but has about the same temperament and attentiveness as a Dick Lebeau. Very intellectual, film room kind of guy that notices the subtle nuances of his opponents and can make adjustments on the fly. Very detail oriented.
They said to expect a very complex and robust defensive playbook, but that he is not going to call a very aggressive game. They expect him to be more of a bend but don't break kind of DC. Has learned under Parcells and Nolan, Nolan generally being the more aggressive of the two. This past season, the Dolphins rushed 6 or more people only 30 times.
Had Dallas in the top 3 in interceptions during his tenure and had the Cleveland Browns lead the league in interceptions with 33 when he was their secondary coach. Cleveland was also ranked 5th in the league in pass defense allowing only 181 yards per game through the air.
All in all, would be a solid hire in my opinion. I think he could get this defense to be very respectable. Would still need to add some key pieces, mainly at rush LB.